Like everything else, bridges are prone to wear and tear, often from environmental elements and constant use. New research out of Utah State University says the use of drones could help identify cracks, and ultimately extend the life of bridges.
"In our study, we were specifically looking at something called a [steel] fatigue crack," said Marc Maguire, a professor in civil and environmental engineering at USU. "Steel, when it undergoes cyclic loading from trucks or wind or sometimes thermal changes, it can develop cracks. Furthermore, cracks that we’re looking for are about the width of a human hair and maybe 7 millimeters long - very small - they are difficult for even a human to find."
Maguire and his colleagues are asking the question: Can a drone perform a bridge inspection up to the level of a human?
They want to see if UAS, Unmanned Arial Systems or commonly known as a drone, can identify these kinds of steel cracks. But using an Unmanned Arial System has its own challenges, like differences in light flying underneath and around the bridge.
"The camera needs to have exposure control because it is a low light environment, and not only is it a low light environment, it is a highly variable light environment," Maguire said. "If you’re flying through and the sun’s on one side, let’s say it is low in the sky on the opposite side of the bridge, you could have a huge amount of light coming in from under the bridge and it’ll wash everything out and so you need to be able to adjust for situations like that as well as low light situations."
Maguire and his colleagues have been using UASs on bridges with known cracks to better understand the difficulties of using the devices in situations with low GPS signaling, low light environments and windy conditions. By better understanding these challenges, future research can focus on solving these problems.
Even though drones have become more prominent in common culture, according to Maguire, human bridge inspections are still the best option today.
"I would not say it was as good as a human inspection, it definitely wasn’t and it would absolutely never be able to replace humans, never is a strong word but very unlikely that we would be able to replace a human inspection," Maguire said.